1. Field of the Invention
This invention relates to a power transmission chain used in vehicles such as a bicycle and a motorcycle and industrial machines, and more particularly, to a chain joint for connecting or disconnecting the power transmission chain.
2. Description of the Prior Art
A bicycle chain, as well as a motorcycle chain, is an endless chain which alternately joins a plurality of outer links and a plurality of inner links with a pin fitted into a bush and caulked at both its ends. If the chain is elongated during use and prone to be off of a sprocket, it has to be disconnected and then connected again after removing some links. In order to disconnect the chain, it is necessary to forcibly pull out the caulked pin using a jig. When re-connecting the chain, on the other hand, the pin which was pulled out must be inserted into pin holes before the being caulked again.
When removing a pin which is firmly caulked by force, however, the pin will be shaved where it is caulked, and the pin holes will be out of shape in part. This may reduce the caulking force which is applied in re-connecting, and may cause the chain to eventually be broken during running because it comes off.
A conventional chain joint is not suitable for repeatedly connecting and disconnecting the chain, and it is troublesome to pull the pin out by force and then to caulk the pin every lime the chain is disconnected and connected again.
On the other hand, a chain for an industrial machine is linked end to end by a joint forming a piece of the chain after it is set onto the sprockets. As shown in FIG. 6, the joint has a long pin 1 and a clip 3. The clip 3 is made of a steel spring and fitted in a circular groove la formed where the pin 1 comes out the pin hole 2 to prevent the pin 1 from coming off.
The joint construction as described above suggests, however, that the chain has to be greater in width W, and the clip 3 may be broken due to metallic fatigue.